Pyrotechnic charges are frequently made by either a casting or an extruding process. Each process is particularly adaptable to specific pyrotechnic compositions and some compositions cannot be cast while others cannot be extruded.
One such casting process for a propellant charge is shown and described in U.S. Pat. No. 3,678,138, entitled, "Solid Propellant Charge Making In Mold Having Perforated Separator Means," which issued July 18, 1972, to Stuart Gordon et al. In this process casting powder, which is principally nitrocellulose, is placed in a mould and a casting liquid is forced through the powder by gas pressure using an inert gas. The propellant is allowed to cure in the mould and, after curing the mould is separated and the propellant charge removed.
An extruding process for forming a pyrotechnic composition is shown and described in U.S. Pat. No. 3,418,686, entitled, "Apparatus For Forming Rocket Propellant Grains," which issued Dec. 31, 1968, to Richard G. Guenter. In this process, an axially movable ram is utilized to extrude propellant through a multiplicity of orifices. The movement of the extruded material is opposed or retarded by a disc shaped consolidation ram positioned in a die segment. The retarding of the movement of the material results in a product having a large propellant grain while at the same time relieving the stresses and strains generated by the extrusion.